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Biomedical subjects

R Plass

Publications and source records attributed to R Plass.

At least 19 recordsLinked to original sources
PubMed2003

Thermal motion and energetics of self-assembled domain structures: Pb on Cu(111).

Low energy electron microscope measurements of the thermal motion of 50-200 nm diameter Pb islands on Cu(111) are used to establish the nature and determine the strength of interactions that give rise to self-assembly in this two-dimensional, two-phase system. The results show that self-assembled patterns arise from a temperature-independent surface stress difference of approximately 1.2 N/m between the two phases. With increasing Pb coverage, the domain patterns evolve in a manner consistent with models based on dipolar repulsions caused by elastic interactions due to a surface stress difference.

Journal Article↗
PubMed2001

Nanostructures. Self-assembled domain patterns.

The ordered domain patterns that form spontaneously in a wide variety of chemical and physical systems as a result of competing interatomic interactions can be used as templates for fabricating nanostructures. Here we describe a new self-assembling domain pattern on a solid surface that involves two surface structures of lead on copper. The evolution of the system agrees with theoretical predictions, enabling us to probe the interatomic force parameters that are crucial to the process.

Journal Article↗
PubMed1998

High and low luminance letters, acuity reserve, and font effects on reading speed.

We compared reading speed with two fonts, Dutch (serif) and Swiss (sans serif). Text was displayed on a computer monitor, white letters on black, with the RSVP method. Luminance of the letters was either 146.0 or 0.146 cd m-2. Lower-case x-height of the fonts was approximately 5.5 times as large as letter acuity. At the high luminance, there was no difference between reading rates. There was a significant advantage for the Swiss font at the low luminance. The acuity reserve for Swiss was higher than for Dutch at the low luminance, which may account for the difference in reading speeds.

Humans↗
PubMed1993

Effects of glucosinolate breakdown products on the hepatic biotransformation system in male rats.

The effects of 5-vinyloxazolidine-2-thione (VOT), 1-cyano-3-butene (CYB) and various isothiocyanates on parameters of hepatic phase I and phase II biotransformation were investigated in male rats after oral treatment for 3 consecutive days. The compounds with the exception of CYB caused increases in liver weight and glutathione S-transferase activity. Cytochrome P-450 level and monooxygenase activities were decreased by the isothiocyanates and CYB. Administration of VOT resulted in contrasting response of monooxygenases: reduced aminopyrine N-demethylation and enhanced aniline hydroxylation. Possible mechanisms were discussed.

Alkenes↗
PubMed1992

Subacute oral toxicity study of benzyl isothiocyanate in rats.

The subacute toxicity of benzyl isothiocyanate (BITC) was investigated in male rats given oral doses of 0, 50, 100 and 200 mg/kg body weight/day for 4 weeks. Body weight gain and food consumption were decreased with increasing doses of BITC. Haematological changes of toxicological relevance were observed in the highest dose group. BITC administration resulted in increased serum cholesterol level in all treatment groups and decreased serum triglycerides level at 200 mg/kg. Renal dysfunction was indicated by reduced urine volume, proteinuria and enhanced urinary lactate dehydrogenase activity. BITC exposure also affected the weights of various organs and caused histological changes in the ductus choledochus, liver, ileum and mesenteric lymph nodes.

Animals↗
PubMed1992

Toxicological evaluation of rapeseed products in a subacute feeding study in rats.

Groups of 15 male rats were fed ad libitum for 4 weeks standard diet containing 0, 2.5, 5 or 10% rapeseed protein isolate (RPI), 2.5, 5 or 10% rapeseed extraction residue (RER) or 10% casein. Body weight gain and food intake were recorded weekly. Clinical chemistry analyses, haematology, urinalysis, organ weights and histology were performed terminally. Serum alanine aminotransferase was decreased by RPI, RER and casein, while serum albumin only increased in rats fed RER. Microscopic examinations revealed abnormalities in liver and kidneys of animals at the 10% RPI, RER and casein levels. The absolute liver weights showed increases in the 5 and 10% RER groups and in the 10% RPI group. The relative kidney weights were reduced at all RER levels and in the 2.5% RPI group. Antithyroid activity of the rapeseed products were not noted.

Alanine Transaminase↗
PubMed1991

[Toxicological effect of a fatty acid mixture in rats].

The effects of a fatty acids mixture containing nearly 50% odd numbered fatty acids (PC-Säure) were studied in a subchronic toxicity test in male and female rats. The animals received PC-Säure in their diet at levels of 0, 1.25, 2.5 and 5% for 13 weeks. Food intake was increased at 5% PC-Säure level in males. Food efficiency was initially decreased in males and females of this group. Ingestion of PC-Säure resulted in increases of the urine volume and the urinary lactate dehydrogenase activity in both sexes. Male and female rats fed PC-Säure showed elevated serum activities of alkaline phosphatase and leucine aminopeptidase and decreases in serum cholesterol and triglycerides. Dietary PC-Säure elevated the serum creatinine content in males at the two highest levels. A transitory increase in the activity of the serum alanine aminotransferase was observed in females fed 5% PC-Säure. Increased liver and kidney weights were found in both sexes.

Alanine Transaminase↗
PubMed1991

[Toxicological evaluation of saccharose carbonic acid esters in basic subchronic feeding trials with rats. 1. Effect of saccharose fatty acid polyester].

Groups of male and female rats received a sucrose fatty acid polyesters containing product (SPE) in their diet for 13 weeks at levels of 0, 5, 10 or 15%. Additional groups were pair-fed to the high-dose SPE-group (standard diet, 92.5%) or given food containing 7.5% hydrogenated lard (HF) or 4.5% fatty acid ethyl ester (FEE). Compared to the controls, there were increases in the food intake in males and females of the SPE-groups, HF- group and FEE-group. Male rats fed SPE showed increases in serum urea nitrogen at all levels, in serum alkaline phosphatase activity and urinary glucose excretion at 10 and 15%, in serum leucine amino-peptidase at 15%. In females dietary SPE increased the blood glucose content and serum alkaline phosphatase activity at 15% and the serum leucine aminopeptidase activity at 10 and 15%.

Alkaline Phosphatase↗
PubMed1991

[Toxicologic evaluation of sucrose carbonic acid esters in basic subchronic feeding studies in rats. 2. Effect of sucroacetoglycerides].

Groups of male and female rats received a sucroacetoglycerides containing product (SAG) for 3 months at dietary levels of 0, 2.5, 5 and 10%. Food consumption was initially increased in females at all SAG-levels. After two weeks significant increases in food intake were observed in males and females fed 10% SAG throughout the feeding period. The serum analysis revealed significantly elevated activity in serum alkaline phosphatase at the highest SAG-level in males and females after 6 weeks and in females after 13 weeks. Histological changes related to the SAG-feeding were noted in the intestinal lymph nodes of male and female animals fed 10% SAG. The no-adverse effect level established in this subchronic feeding study was 5% SAG in the diet of rats, equivalent to a daily intake of 3.6 g/kg body weight in males and 4.0 g/kg in females.

Acetates↗
PubMed1990

[The subacute toxicity of glucosylthiazolidine-4-carbonic acid in rats].

Glucosylthiazolidine-4-carbonic acid, an intermediate of the Maillard reaction between D-glucose and L-cysteine, was given in doses of 0, 25, 50 or 100 mg/kg b.w. by oral intubation to male and female rats for 21 days. General appearance, growth, food consumption, haematology, urine analysis and serum chemistry including determinations of enzyme activities, organ weights and macroscopic and microscopic pathology were used as criteria for adverse effects. Effects on the kidneys were indicated by oliguria and decreased specific gravity of the urine in males and histopathological changes of the proximal tubules in females. The no-effect dose established from this study is 25 mg/kg b.w.

Animals↗
PubMed1989

[The subchronic toxicity of 5-vinyloxazolidine-2-thione in rats].

Groups of male and female rats received 5-vinyloxazolidine-2-thione (VOT) in their drinking water for 13 weeks at concentrations of 0, 10, 25, 50 or 100 mg/l and 0, 2.5 or 5 mg/l respectively. Compared with the controls, there were decreases in food intake and growth of females given VOT-doses of 10 mg/l and higher. Liquid intake was reduced in males and females of the highest dose group. Terminal haematological examination revealed an increase in white cell count at the 50 and 100 mg levels in females and a reduction in the red cell count at 100 mg/l in males. Organ weight changes were dose-related increases in the relative thyroid and liver weight and a decrease in the relative thymus weight. Structural and functional changes of the thyroid were observed in animals at levels of 10 mg/l and higher. Histological examinations of the kidneys showed tubulonephrosis in animals at and above a VOT-level of 5 mg/l. The no-observed-effect level (NOEL) established from these studies was 2.5 ml VOT/l drinking water (approximately equivalent to an daily intake of 0.4 mg/kg body weight).

Animals↗
PubMed1989

[Distribution and metabolism of azoxybenzene in the rat].

No sex differences could been shown after absorption and distribution of azoxybenzen in the rat. The highest level occur in the thyroid gland, the adrenals and in the fat tissues. The maximum level was reached 30 min. after application.

Animals↗
PubMed1989

[Early indicators of kidney injury in male and female rats after oral administration of cadmium].

The effect of cadmium on the urinary excretion of glucose, creatinine and enzymes has been studied in adult male and female rats given the substance (70, 140 and 280 mg/kg food) for 4 weeks. Renal function tests and gel electrophoresis of urinary proteins were conducted simultaneously. Sex-dependent differences were demonstrated with regard to sensitivity of several kidney parameters and their predictive character of a possible chronic nephrotoxicity. These results were compared with hematological and general biological examinations of cadmium toxicity.

Animals↗